Optical fiber cables are implemented in communications systems for transmitting information between a laser transmitter and a receiving photodiode. Some optical fiber cables, such as premises cables, are intended to be handled by persons from time to time and, therefore, must be manufactured so that handling of the optical fiber cables will not damage the cables or interfere with signals being transmitted over the cables. Some optical fiber cables manufactured for this purpose are commonly referred to as miniature jumper cables. Each miniature jumper cable commonly is comprised of the fiber itself, which typically is comprised of glass, a fiber buffer surrounding the fiber, which typically is comprised of nylon, an aramid fiber strength member surrounding the fiber buffer, and an outer sheath surrounding the aramid fiber strength member, which typically is comprised of PVC that is opaque.
Duplex optical fiber cables comprise a pair of miniature jumper cables that are attached to each other along the lengths of the jumper cables to form a cable that looks similar to a lamp chord. One of the miniature jumper cables corresponds to the transmit jumper cable and the other miniature jumper cable corresponds to the receive jumper cable. The ends of each of the jumper cables has a connector attached thereto which is used to connect the jumper cables to other devices, such as to an optical transmitter and an optical receiver.
In order to distinguish the transmit jumper cable from the receive jumper cable, manufacturers of duplex cables typically mark one of the jumper cables. For example, it is known to place a stripe of ink along the length of one of the jumper cables of the duplex cable. It is also known to print lettering on one of the jumper cables of the duplex cable, such as the name of the manufacturer of the cable. These markings allow a technician to easily distinguish between the transmit and receive jumper cables. However, placing markings on one of the jumper cables is not an easy task and is prone to error. In fact, one of the greatest wastes of optical fiber cable in the optical fiber cable industry is attributable to cable which is discarded because of inaccurate printing on the cable. Furthermore, when the cables are wound up on reels, as is often the case, the markings are often difficult to see.
Another way to distinguish the transmit jumper cable from the receive jumper cable is to physically remove a portion of the outer sheath of the jumper cable and a portion of the aramid strength member to expose the fiber buffer. It is common in the optical fiber cable industry to use colored buffers. A well known industry standard defines the colors that are used for buffers of different optical fiber cables in order to distinguish between optical fiber cables. The color of the buffer of an optical fiber cable may be determined by looking at the end of the optical fiber cable. However, once a connector has been placed on the end of the optical fiber cable, the buffer is no longer visible.
Therefore, if the cables are not marked in such a manner that the cables can be distinguished, the cables can only be distinguished by removing a portion of the outer sheath and of the aramid strength member so that the color of the buffer is ascertainable. However, in attempting to remove a portion of the sheath and of the aramid strength member, a technician may inadvertently damage the fiber itself Accordingly, a need exists for a method of providing optical fiber cables with a distinguishing characteristic that does not require marking of the cables and that allows the cables to be easily distinguished without piercing the cables. Each of the jumper cables is color coded, either in accordance with one of the color-coding techniques of the present invention or in accordance with a conventional color-coding technique. The color code of each of the jumper cables can easily be ascertained through the outer light-transmissive jacket of the quad cable.
In accordance with a fourth embodiment of the present invention, a six-fiber break-out cable comprising six optical fiber miniature jumper cables has an outer light-transmissive jacket. Each of the jumper cables is color coded, either in accordance with one of the color-coding techniques of the present invention or in accordance with a conventional color-coding technique. The color code of each of the jumper cables can easily be ascertained through the outer light-transmissive jacket of the break-out cable.
Other features and advantages of the present invention will become apparent from the following discussion and claims, as well as from the drawings.